Integrated Weed Management Systems

Transcription

1 Integrated Weed Management Systems Jamshid Ashigh, Ph.D. Extension Weed Specialist/ Assistant Professor Integrated Weed Management (IWM) The sustainable use of all available methods to reduce weed pressure without reducing farm income and damaging the environment. Integration of effective and environmentally safe weed control methods. 1

2 Conventional Weed Management The main emphasis is on herbicides. There have been many concerns with regard to environmental, economic and social impacts of agriculture and its sustainability. The reduction of pesticide use has become an important objective in both agricultural policy making and research. Use of Insecticides and Fungicides The per hectare use of insecticides and fungicides in agriculture has dramatically reduced Integrated Pest Management (IPM) programs (combined use of cultural, biological, mechanical and better pest monitoring). In 1960s insecticides and fungicides dominated the agricultural pesticide market (nearly 80% of agricultural pesticide use). Since 1990s less than 50% of used agricultural pesticides are insecticides and fungicides 2

3 Use of Herbicide Herbicide use on a per hectare basis, has not declined at the same rate as fungicides and insecticides (herbicides( have accounted for half of the agricultural pesticide use since 1990). Use of pre-emergence herbicides based on the anticipated weed populations. Preventative strategies Integration of mechanical, cultural and biological methods in our weed management practices Precision agriculture Organic Weed Management Preventative strategies Integration of mechanical, cultural and g biological methods in our weed management practices Precision agriculture 3

4 Organic Weed Management Weeds are the most serious threat to organic crop production and one of the major obstacles to conversion from conventional to organic farming. Organic producers mainly rely on mechanical cultivation for weed control. Negative impact the soil and water conservation Cultivation can help weed germination Not cost-effective (Penfold et al., 1995; Stonehouse et al., 1996; Clark et al., 1998; Beveridge & Naylor, 1999) IWM With the IWM approach each practice (e.g., herbicides) supplement other practices rather than serve as the sole tactic for weed control. The main emphasis is on: Prevention Enhancing crop competition Reducing weed density 4

5 Prevention Prevention focuses on keeping new weeds out and preventing the further spread of weed seed or perennial plant parts. Preventing weed infestation. Early detection/rapid response. Enhancing Crop Competition Crop interaction with weeds varies with crop, weed species and environment conditions, but in an area, any plant that t captures resources first gains a competitive advantage over neighboring plants. (Mortimer, 1984). Variety selection Seeding rates Row spacing Fertilizer placement Precision agriculture 5

6 Precision Agriculture An agricultural practice based on in-field variability. It requires the use of new technologies, such as global positioning, sensors and information management tools to assess and understand variations. Estimate pesticides and fertilizers needs in different locations of the farms. Maximize profits and reduce negative environmental impacts by placing herbicides and fertilizer where it needed. Reducing Weed Density Continues cropping practices that comprise crops with similar life cycles will increase weed density (Froud-william, 1988). Rotation Diversifying the cropping systems with crops of different lifecycle Could help other pest management issues Different planting and harvest times Prevent plant establishment and seed production 6

7 Reducing Weed Density Tillage Rotational tillage options Flaming Reduce soil disturbance Cover crops and mulches Physical weed suppression Limiting light availability. weblog.clagettfarm.org/2004/10/cover_crops.html Chemical weed suppression Releasing allelopathic chemicals. Wheat, rye, oat, sorghum and Cole crops such as broccoli and wild radish Reducing Weed Density Herbicides Chemicals are more effective if applied based on the label l directions. i Weed threshold Scythe, corn gluten, clove oil, etc. 7

8 Integrated Weed Management: A Case Study Optimizing weed management in semiarid great plains by ecological approach. Colorado, Wyoming, Kansas and Nebraska Winter wheat-fallow has been the predominant cropping system. Compensate for the erratic precipitation No crops or weeds during the fallow (increase soil moisture) it (Anderson, 2003) Integrated Weed Management: A Case Study Similar life cycle of winter wheat with annual grasses such as jointed goatgrass and downy brome has increased their density. Not many herbicide options Herbicide resistance. Reliance on the same herbicides (Anderson, 2003) 8

9 Integrated Weed Management: A Case Study No-till system has provided more cropping options. More crop residues left on the ground Increased soil moisture. Producers have been changing their cropping systems to incorporate more crops in rotations with winter wheat. Winter wheat corn sunflower fallow or winter wheat corn proso millet fallow Improved net return Reduced total weed density and control of winter annual grasses (Anderson, 2003) Integrated Weed Management: A Case Study Fallow in rotations would help weed control but in terms of long term soil productivity fallow, could be detrimental. Erosion and loss of organic matter Research has shown that winter wheat corn proso millet dry pea can be more beneficial. (Anderson, 2003) 9

10 Summary Integrated Weed Management is a system approach to weed control. Designed based on the merits of each environment to minimize the losses caused by weeds without reducing farm income and damaging the environment 10